1. Field of the Invention
The present invention relates to landing gear assemblies for supporting trailers and, more particularly, to an improved air bladder actuated landing gear assembly including an airbag lift and a safety latch and lock mechanism.
2. Description of the Prior Art
Typical landing gear assemblies for semi-trailers and the like include a pivoting or vertically movable support assembly, with bottom foot pads or steel wheels, which are hand cranked into a supporting position, so as to support the semi-trailer in a level attitude when the tractor is withdrawn. More recent developments have included hydraulic or air pressure operated landing gear, either pivoted or vertically lowered into the trailer supporting position.
Prior art patents will be discussed in order of their perceived relevance to the instant invention. U.S. Pat. No. 3,904,224 issued Sep. 9, 1975, to Jack T. Belke discloses a landing gear assembly with extensible legs, each part of the assembly being attached tangentially to the trailer being supported, rather than directly therebeneath. No specific actuator is shown for moving the support legs down into a supporting position and the air bladder construction in an enlarged chamber and safety latch and lock mechanism of the instant invention are not taught by Belke.
A wheel lift construction for increasing the load capacity of a vehicle and including an air bag for extending a pair of dolly wheels, and further including a return spring assembly for retracting the wheels when the bag is deflated is seen in U.S. Pat. No. 4,711,464 issued Dec. 8, 1987, to Michael Bilas. However, this patent does not teach either the large load capacity air lift bladders and simplified extensible leg construction or the safety latch and lock mechanism of the instant invention.
A pin and hole latch mechanism for locking landing gear assembly legs in their extended position is disclosed in the Soviet Union Patent No. 1599252 dated Oct. 15, 1990, to Avtotranstekhnika, and the legs are hydraulically extended into a supporting position; the legs are pivoted about ninety degrees to a storage or stowed attitude. The safety latch and lock assembly of the instant invention is not taught in this particular patent.
Other, somewhat more remote prior art disclosures are found in the following patents. U.S. Pat. No. 3,874,696 issued Apr. 1, 1975 to Clifford C. Gardner discloses a support for semi-trailers with a pair of adjustable legs which are pivotally displaced between raised and lowered positions, there being an air cylinder to effect displacement of the legs. Another landing gear assembly but including an electric motor for raising and lowering the landing gear is seen in U.S. Pat. No. 4,097,840 issued Jun. 27, 1978, to Warner A. Chappelle; the motor is operable from the cab of the tractor through electrical circuitry. A mechanical undercarriage assembly including feet automatically retracted when the trailer is hitched and connected to a tractor is taught in U.S. Pat. No. 4,150,840, issued Apr. 24, 1979, to Tara N. Banerjea et al. The improvements of this invention are not disclosed.
U.S. Pat. No. 5,299,829 issued Apr. 5, 1994 to Bernard A. Rivers et al. teaches a pneumatic system for trailer landing gear, but the system is coupled to the conventional gear box and gear drive of such a landing assembly, rather than directly to the landing gear as in the instant invention. The following domestic and foreign patents include disclosures of related but remote landing gear assemblies: U.S. Pat. Nos. 2,572,410 issued Oct. 23, 1951, to Hubertus J. Van Doorne; 4,930,977 issued Feb. 27, 1990, to Bobby G. Baxter; 5,188,379 issued Feb. 23, 1993, to Hans H. Krause et al.; and 5,340,143 issued Aug. 23, 1994, to Thomas M. Williams, Jr.; European Patent No. 0 195 282 dated Feb. 26, 1986, to Jost-Werke GMBH; and Soviet Union Patent No. 1583319 dated Aug. 7, 1990, to N Ind Res Inst.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.